Transfer printing machine

ABSTRACT

Machine for transfer pattern printing of a textile web, said machine comprising a centre roller ( 1 ), at least one pressure roller ( 2 ), a tension roller ( 3 ), a reversing roller ( 4 ) and an endless belt ( 5 ) which is of a width substantially corresponding to the length of the pressure roller ( 2 ). The endless belt ( 5 ) extends about the tension roller ( 3 ) and the reversing roller ( 4 ), and a first portion ( 8 ) of the periphery of the pressure roller ( 2 ) abuts and exerts a pressure on the centre roller ( 1 ). While in continuous contact with one another, a pre-printed pattern-carrying web ( 6 ) and the textile web ( 7 ) can pass between the centre roller ( 1 ) and the pressure roller ( 2 ) and here be subjected to a local compression. The endless belt ( 5 ) is guided around a second portion ( 9 ) of the periphery of the pressure roller ( 2 ), said second portion being positioned substantially diametrically opposite the first portion ( 8 ) of said periphery of the pressure roller, whereby the pressure exerted by the pressure roller ( 2 ) on the centre roller ( 1 ) is adjustable by an adjustment of the tension in the endless belt ( 5 ) by means of the tension roller ( 3 ).

TECHNICAL FIELD

The invention relates to a machine for transfer pattern printing oftextile webs, said machine comprising a centre roller, at least onepressure roller, a tension roller, a reversing roller and an endlessbelt which is of a width substantially corresponding to the length ofthe pressure roller and which extends about the tension roller and thereversing roller, and where a first portion of the periphery of saidpressure roller abuts and exerts a pressure on said centre roller withthe result that a pre-printed pattern-carrying web and the textile webare subjected to a local compression, said preprinted pattern-carryingweb and said textile web being in contact with one another and passingbetween said centre roller and said pressure roller.

BACKGROUND ART

Transfer pattern printing is a technique involving a continuous transferof a pre-printed pattern from a pattern-carrying web to the textile web,where the two webs are continuously brought into contact with oneanother in a transfer region which is frequently in the form of one ormore pairs of pressure rollers.

Transfer pattern printing is a technique which has been used for a longtime and which has been commercially interesting since the 19-fifties,especially in form of sublimation transfer printing for use inconnection with printing on textile webs of synthetic fibres. Comparedto a direct textile printing, the latter sublimation transfer printingensures the advantage that it is possible very quickly to adapt theproduction to other patterns in such a manner that it is only necessaryto keep a stock of the designs presenting an actual demand. The directtextile printing necessitates, however, in practice often the productionof rather large stocks of the individual designs in order to maintainthe costs per printed unit of length of the textile web at a reasonablelevel.

Another advantage obtained by the transfer pattern printing is found inthe fact that it is possible to obtain a rather sharp and finelydetailed transfer of the patterns, said patterns in advance beingprinted by means of suitable dyes and with the required fineness andsharpness on a suitable pattern-carrying web.

As a result of the above, the transfer pattern printing has graduallybecome highly interesting, and various types of the technique has beendescribed in several publications within the patent literature.

U.S. Pat. No. 4,057,864 describes a machine which according to thepreamble of claim 1 is to be used for wet transfer pattern printing, andwhere the pattern-carrying web and the textile web held together one ontop of the other are moved about the centre roller and kept in contacttherewith by means of an endless belt guided around a portion of theperiphery of said centre roller. Some pressure rollers along theperiphery of the centre roller provide local compressions of thepattern-carrying web and the textile web.

The transfer pattern printing and other types of roller processes areencumbered with the general problem of obtaining a uniform, linearpressure in the entire length of said rollers, i.e. in the entire widthof the textile web, said width often being several meters. This problemis caused by the rollers of one pair of rollers exclusively beingsupported at the ends. Thus both rollers curve away from one another inthe middle due to the pressure, which results in a less linear pressurein the middle. In turn the latter causes a non-uniform transfer of theprinted pattern from the pattern-carrying web to the textile web, saidtransfer often being insufficient in the middle. This problem growsalong with an increase of the length of the rollers used and along withan increase of the linear pressure required.

DK-PS No. 169,135 discloses a process for transfer pattern printing of atextile web between pairs of rollers under such a high pressure that thetransfer of the pattern from the pattern-carrying web to the textile webcan be carried out without the use of heat. The above problem ofobtaining a uniform linear pressure applies in particular to thisprocess because a linear pressure of up to 50 kg/cm is used by thisprocess.

Previously, attempts have been made at solving this problem by means ofparticular pressure rollers where the interior of said roller issubjected to a radially outward pressure by means of a hydraulic fluidin such a manner that the surface of said roller is sufficientlydeformed so as to ensure a uniform linear pressure in the entire lengthof said roller. A system using such rollers is, however, encumbered withthe drawback that it is very expensive to produce because it requires acomplete hydraulic system with pumps, reservoirs, hydraulic pipes andcomplicated gaskets between the mutually movable parts.

BRIEF DESCRIPTION OF THE INVENTION

The object of the invention is to provide a machine for transfer patternprinting, where it is possible even in connection with very high linearpressures to obtain a uniform linear pressure in the entire width of thetextile web.

The machine for transfer pattern printing is according to the inventioncharacterised in that the endless belt is guided around a second portionof the periphery of the pressure roller, said second portion beingpositioned substantially diametrically opposite the first portion ofsaid periphery of the pressure roller, whereby the pressure exerted bythe pressure roller on the centre roller is adjustable by an adjustmentof the tension in the endless belt by means of the tension roller. Theresulting linear pressure exerted by the pressure roller on the centreroller is uniform in the entire length of said pressure roller becausesaid pressure roller is subjected in its entire length to a uniformlinear force by the endless belt.

According to a preferred embodiment, the endless belt is guided around asubstantial portion of the periphery of the centre roller and throughthe nip between the pressure roller and the centre roller. As a result areliable guidance of the pattern-carrying web and the textile webbetween the endless belt and the centre roller is obtained, and inaddition to the local compression in the nip between the pressure rollerand the centre roller a further comparatively weaker compression isobtained of the two webs across an increased portion. The latter can beadvantageous in connection with the transfer of the pattern from thepattern-carrying web to the textile web.

The endless belt is preferably made of a waterproof, essentiallynon-stretchable material, whereby it is ensured that the pressure rollercan subject the centre roller to a sufficiently high linear pressure,and that fluid and dye are not sucked out of the textile web.

The endless belt is preferably made of an aramide-fibre reinforced(Kevlar®) rubber blanket presenting a high ultimate stress, a highelastic modulus, dimensional stability and an outstanding resistance tomoisture.

The machine may according to a preferred embodiment comprise twopressure rollers, which turned out to increase the transferring effect.

One or more of the rollers, preferably the reversing roller, may presenta convex (bombé) cylindrical surface. As a result an increasedtensioning of the endless belt is obtained in the middle, whereby saidbelt does not move towards the ends of the rollers during operation. Inaddition, this tensioning assists in ensuring that the linear pressureis equally high at the middle of the pressure roller as well as at theends of said pressure roller.

According to a preferred embodiment, the reversing roller is the drivingroller which in connection with the rotation drives the remainingrollers and the endless belt.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is described in greater detail below with reference to theaccompanying drawing, in which

FIG. 1 is a diagrammatic view of a machine according to the invention,and

FIG. 2 is a diagrammatic view of a preferred embodiment of a machineaccording to the invention.

BEST MODE FOR CARRYING OUT THE INVENTION

The machine shown in FIG. 1 for transfer pattern printing of a textileweb comprises a centre roller 1, a pressure roller 2, a tension roller3, a reversing roller 4 and an endless belt 5. A textile web 7 to beprinted is wound off an unwind roll 10 and brought into contact with apattern-carrying web 6. The pattern-carrying web is wound off an unwindroll 11 and guided into the transfer region between the pressure roller2 and the centre roller 1. While passing from the roll 10 to the centreroller 1, the textile web 7 is carried through an impregnating unit 17in which said web 7 is immersed in a fluid bath 18 and subsequentlycarried through a pair of rollers 15, 16 pressing as much fluid out ofsaid textile web as possible whereby the resulting web contains anexactly defined residual moisture. The textile web 7 and thepattern-carrying web 6 are joined at a speed of up to 50 m/minute,preferably 10 to 20 m/minute, and carried between the centre roller 1and the pressure roller 2 exerting a linear pressure of up to 50 kg/cm.As a result, a predetermined quantity of moisture is pressed out of thetextile web 7 with the effect that said textile web 7 soaks thepattern-carrying web and consequently the carrier for the dye. In thismanner the carrier is activated, viz. swells, whereby the dye is pressedvery quickly—i.e. in a split second—into or penetrates far into thetextile web 7. This effect is intensified by the moist textile web 7initially being compressed and subsequently after leaving the pair ofrollers by said web absorbing the dye and the carrier. Then the textileweb 7 and the pattern-carrying web 6 leave the centre roller 1 and arewound on the rolling-up rolls 12 and 13. In a first portion indicated bythe reference numeral 8, the pressure roller 2 is in contact with thecentre roller 1, and in a second portion 9 positioned diametricallyopposite said first portion said pressure roller 2 is in contact withthe endless belt 5. The endless belt 5 is guided around the reversingroller 4 and the tension roller 3. The tension roller 3 can bevertically moved by means of a pneumatic cylinder 14 in a direction awayfrom said reversing roller 4 so as to tighten the endless belt 5. Atightening of the endless belt 5 increases the pressure on the pressureroller 2 and consequently the pressure of said pressure roller on thecentre roller 1. The endless belt 5 is of a width corresponding to thelength of the pressure roller 2, and accordingly said belt subjects saidpressure roller 2 to a uniform linear pressure in the entire length ofsaid pressure roller which in turn exerts a uniform linear pressure onthe centre roller 1. In order to provide a linear pressure of up to 50kg/cm, the endless belt 5 is made of an aramide-fibre reinforced(Kevlar®) rubber blanket. At the ends the pressure roller 2 is mountedin guides (not shown) whereby said pressure roller can be moved towardsand away from the centre of the centre roller 1.

FIG. 2 shows a preferred embodiment of a machine for transfer patternprinting according to the invention. The machine of FIG. 2 differs fromthe machine of FIG. 1 by comprising two pressure rollers 2 and by theendless belt 5 extending around a substantial portion of the peripheryof the centre roller 1 and through the nip between said pressure rollers2 and said centre roller 1. As a result the textile web 7 and thepattern-carrying web 6 are compressed along the entire portion of theperiphery of the centre roller 1 which is surrounded by the endless belt5. In addition, the webs are compressed locally between he pressurerollers 2 and the centre roller 1. This structure turned out to beparticularly advantageous because the textile web and thepattern-carrying web are smoothed out between the endless belt 5 and thecentre roller 1 before they reach the first pressure roller 2. When thetextile web and the pattern-carrying web leave the first pressure roller2, said webs are reliably fixed relative to one another between theendless belt 5 and the surface of the centre roller 1 until they reachthe second pressure roller 2 where they are again subjected to a highlinear pressure with the result that the transferring effect isintensified.

The invention is not restricted to the above embodiments. Three or morepressure rollers can for instance be arranged along the periphery of thecentre roller.

1. A machine for transfer pattern printing of a textile web, saidmachine comprising a center roller, at least one pressure roller, areversing roller, a tension roller that can move towards and away fromthe reversing roller and an endless belt, which is of a widthsubstantially corresponding to a length of the pressure roller and whichextends about the tension roller and the reversing roller, and where afirst portion of a periphery of said pressure roller abuts and exerts apressure on said center roller with a result that a pre-printedpattern-carrying web and the textile web are subjected to a localcompression because said pre-printed pattern-carrying web and saidtextile web are in contact with one another and pass between said centerroller and said pressure roller, wherein the endless belt is guidedaround a second portion of the periphery of the pressure roller, saidsecond portion being positioned substantially diametrically opposite thefirst portion of said periphery of the pressure roller, whereby thepressure exerted by the pressure roller on the center roller isadjustable by an adjustment of a tension in the endless belt by movingthe tension roller towards or away from the reversing roller.
 2. Themachine as claimed in claim 1, wherein the endless belt is guided arounda substantial portion of a periphery of the center roller and through anip between the pressure roller and said center roller.
 3. The machineas claimed in claim 1, wherein the endless belt is made of a waterproof,essentially non-stretchable material.
 4. The machine as claimed in claim1, wherein the endless belt is made of an aramide-fiber reinforcedrubber blanket.
 5. The machine as claimed in claim 1, wherein themachine comprises two pressure rollers.
 6. The machine as claimed inclaim 1, wherein one or more of the rollers comprise(s) a convexsurface.
 7. The machine as claimed in claim 6, wherein the reversingroller comprises the convex surface.
 8. The machine as claimed in claim6, wherein a cylinder can move the tension roller towards and away fromthe reversing roller.
 9. The machine as claimed in claim 1, wherein thereversing roller is driving.